Aquaporin 1, 3, and 5 Patterns in Salivary Gland Mucoepidermoid Carcinoma: Expression in Surgical Specimens and an In Vitro Pilot Study.

Salivary gland aquaporins (AQPs) are essential for the control of saliva production and maintenance of glandular structure. However, little is known of their role in salivary gland neoplasia. Salivary gland tumors comprise a heterogeneous group of lesions, featuring variable histological characteristics and diverse clinical behaviors. Mucoepidermoid carcinoma (MEC) is the most common salivary gland malignancy. The aim of this study was to evaluate the expression of AQP1, AQP3, and AQP5 in 24 MEC samples by immunohistochemistry. AQP1 expression was observed in vascular endothelium throughout the tumor stroma. AQP3 was expressed in epidermoid and mucosal cells and AQP5 was expressed in mucosal cells of MEC. These proteins were expressed in the human MEC cell line UH-HMC-3A. Cellular ultrastructural aspects were analyzed by electron microscopy to certificate the tumor cell phenotype. In summary, our results show that, despite the fact that these molecules are important for salivary gland physiology, they may not play a distinct role in tumorigenesis in MEC. Additionally, the in vitro model may offer new possibilities to further investigate mechanisms of these molecules in tumor biology and their real significance in prognosis and possible target therapies.

Molecular Aspects of Mucoepidermoid Carcinoma and Adenoid Cystic Carcinoma of the Salivary Gland.

BACKGROUND: Salivary gland tumors (SGTs) are rare and highly heterogeneous lesions, making diagnosis a challenging activity. In addition, the small number of studies and samples evaluated difficults the determination of prognosis and diagnosis. Despite the solid advances achieved by research, there is still an intense need to investigate biomarkers for diagnosis, prognosis and that explain the evolution and progression of SGTs. METHODS: We performed a comprehensive literature review of the molecular alterations focusing on the most frequent malignant SGTs: mucoepidermoid carcinoma and adenoid cystic carcinoma. RESULTS: Due to the importance of biomarkers in the tumorigenenic process, this review aimed to address the mechanisms involved and to describe molecular and biomarker pathways to better understand some aspects of the pathophysiology of salivary gland tumorigenesis. CONCLUSIONS: Molecular analysis is essential not only to improve the diagnosis and prognosis of the tumors but also to identify novel driver pathways in the precision medicine scenario.

TGFß signaling pathway in salivary gland tumors.

OBJECTIVE: Pleomorphic adenoma (PA), mucoepidermoid carcinoma (MEC), and adenoid cystic carcinoma (ACC) are the most prevalent salivary gland tumors. Their pathogenesis has been recently associated with complex molecular cascades, including the TGFß signaling pathway. The aim of this study was to evaluate the expression of genes associated with the TGFß signaling pathway (TGFB1, ITGB6, SMAD2, SMAD4, FBN1, LTBP1, and c-MYC) to map possible downstream alterations in the TGFß cascade. DESIGN: Thirteen PA, 17 MEC, 13 ACC, and 10 non-neoplastic salivary gland samples were analyzed by real-time RT-PCR. RESULTS: Cases of PA presented increased TGFB1, LTPB1, c-MYC, and FBN1 expressions, whereas SMAD2 expression was decreased when compared to non-neoplastic tissue. MEC patients displayed increased expressions of TGFB1, ITGB6, FBN1, and c-MYC and decreased expressions of SMAD2 and SMAD4. ACC cases exhibited elevated expressions of the investigated genes except TGFB1. The present results suggest that decreased expression of SMAD2 and SMAD4 does not impede the transcriptional regulation of c-MYC, especially in PA and MEC. Increased expressions of ITGB6, TGFB1, LTBP1, and FBN1 appear to be related to the regulation of the TGFß signaling pathway in these tumors. Additionally, we observed a higher expression of SMAD4 in ACC and a raised expression of ITGB6 and lowered expression of SMAD2 in MEC. CONCLUSIONS: Our study demonstrated the differential expression of TGFß cascade members in salivary gland tumors such as SMAD2/SMAD4 and c-MYC as well as the participation of ITGB6, TGFB1, LTBP1, and FBN1, contributing to the understanding of the mechanisms involved in tumor progression.

Avaliação da expressão gênica associada à via de sinalização TGFß em tumores de glândulas salivares / Expression evaluation of genes associated with the TGFß signaling pathway in salivary gland tumors

As glândulas salivares são estruturas formadas por um sistema de ductos e ácinos responsáveis por secretar saliva. Apesar de raros, os tumores de glândulas salivares compreendem um grupo heterogêneo de lesões, apresentando diferentes características histológicas, sendo de difícil classificação e comportamento clínico diverso. A identificação de novos marcadores moleculares tem sido alvo de pesquisas para melhor compreensão e classificação dessas neoplasias, visto que a avaliação da expressão gênica e suas vias envolvidas permite identificar genes associados à regulação que modula o desenvolvimento neoplásico. Assim, novos achados podem direcionar a aplicação de novas técnicas para o diagnóstico, prognóstico e tratamento terapêutico. Contudo, pouco se sabe sobre a via de sinalização TGFß em neoplasias mais comuns em glândulas salivares, como: Adenoma Pleomórfico (AP), Carcinoma Mucoepidermoide (CME) e Carcinoma Adenoide Cístico (CAC). Diante disso, torna-se necessário ampliar a pesquisa de genes associados para a determinação de um painel de marcadores e, deste modo, fornecer informações que possam contribuir com o diagnóstico dessas neoplasias. O objetivo desse trabalho foi avaliar a expressão gênica relacionada à via de sinalização TGFß por meio da técnica de RT-PCR em tempo real (qPCR) destacando os marcadores TGFß1, ITGB6, SMAD2, SMAD4, FBN1, LTBP1 e c-MYC. Para tanto, foram selecionadas 13 amostras de AP, 17 de CME e 13 de CAC, além de 10 amostras de glândulas salivares não neoplásicas provenientes de cirurgias realizadas no A.C.Camargo Cancer Center no período do ano 2000 a 2015 e fornecidas pelo Biobanco de Tumores. Os resultados indicam que em pacientes com AP há aumento da expressão dos genes TGFß1, LTPB1, c-MYC e FBN1, enquanto a expressão de SMAD2 diminui quando comparados às amostras não neoplásicas. Em pacientes com CME, foi observada expressão aumentada dos genes TGFß1, ITGB6, FBN1 e c-MYC enquanto a expressão dos genes SMAD2 e SMAD4 diminui ao serem comparados às amostras não neoplásicas. Nos pacientes com CAC, foi observada expressão aumentada em quase todos os genes avaliados. Na análise de clusterização hierárquica não foi possível classificar nas diferentes neoplasias de glândula salivar. Para a validação dos resultados de expressão gênica foi realizada uma meta-análise utilizando dados da literatura, sendo possível observar concordância nos valores de expressão dos genes ITGB6, LTBP1 e TGFß1 em amostras de CME e dos genes FBN1, ITGB6, LTBP1, c-MYC, SMAD2 e SMAD4 nas amostras de CAC. Comparando-se a expressão dos genes entre os três tipos de neoplasias estudados, foi observado aumento de expressão dos genes c-MYC, SMAD2 e SMAD4 nos casos de CAC e aumento da expressão do gene ITGB6 nos casos de CME. A análise de sobrevida demonstrou que, em pacientes com Carcinoma Mucoepidermoide foi observado que a ausência de linfonodo comprometido e ausência de recidiva estão associadas a melhor probabilidade de sobrevida global em 5 anos. Nossos resultados sugerem que a expressão diminuída dos genes SMAD2 e SMAD4 parece não interferir na regulação transcricional de c-MYC, especialmente no AP e CME. Considerando os genes ITGB6, TGFß1, LTBP1, FBN1 e c-MYC a expressão aumentada parece ser relevante para a regulação da via de sinalização no processo de tumorigênese. Sendo assim, este estudo contribui para um melhor entendimento da via de sinalização TGFß em neoplasias de glândulas salivares, além de fornecer informações para o desenvolvimento de potenciais marcadores biológicos para essas neoplasias.

Salivary glands are structures formed by a system of ducts and acini responsible for secreting saliva. Although rare, salivary gland tumors comprise a heterogeneous group of lesions, presenting different histological features, difficult classification, and diverse clinical behavior. Identification of new molecular markers has been the subject of researchers for better comprehension and classification of these tumors, since gene expression evaluation and their signaling pathways allow the identification of genes associated with regulation that modulated tumor development. Therefore, new findings can direct the application of new technologies for diagnosis, prognosis, and therapeutic treatment. However, little is known about the TGFß signaling pathway in the most common salivary gland tumors, such as: Pleomorphic adenoma (PA), mucoepidermoid carcinoma (MEC), and adenoid cystic carcinoma (ACC). In addition, it is necessary to expand research of genes and associated genes for determining a panel of markers and, thus, provide information that could be contribute with the diagnostic of these neoplasms. The aim of this study is to evaluate the expression of genes associated with the TGFß signaling pathway by real-time RT-PCR (qPCR) highlighting the markers TGFß1, ITGB6, SMAD2, SMAD4, FBN1, LTBP1, and c-MYC. For this purpose, 13 PA samples, 17 MEC samples, 13 ACC samples, and histologically normal salivary glands samples were selected from surgeries performed at A.C.Camargo Cancer Center between 2000 and 2015. These samples were provided by Tumor Biobank. The results indicate that PA patients presented an increased TGFß1, LTPB1, c-MYC, and FBN1 gene expression whereas SMAD2 expression was decreased when compared to the normal samples. In MEC patients, increased expression of TGFß1, ITGB6, FBN1, and c-MYC genes was observed whereas SMAD2 and SMAD4 genes presented decreased expression. In ACC patients, increased expression in almost all genes was observed. In hierarchical clustering analysis it was not possible to classify the different salivary gland tumors. For the validation of the gene expression results it was carried out a meta-analysis using the literature date, being possible to observe an agreement in the expression values of the genes ITGB6, LTBP1 and TGFß1 in MEC samples and FBN1, ITGB6, LTBP1, c-MYC, SMAD2 and SMAD4 in ACC samples. Comparing gene expression among the three tumor types studied it was observed higher expression of c-MYC, SMAD2 and SMAD4 genes in ACC cases and higher expression of ITGB6 in MEC cases. Survival analysis demonstrated that, in MEC patients it was observed that absence of affected lymph nodes and absence of recurrence are associated with better overall survival in 5 years. Our results suggest that the decreased expression of SMAD2 and SMAD4 genes seems not to interfere with the transcriptional regulation of c-MYC, especially in PA and MEC. Considering ITGB6, TGFß1, LTBP1, FBN1 and c-MYC increased gene expression appears to be relevant for the regulation of the signaling pathway in tumorigenic process. Thus, this study contributes to a better understanding of TGFß signaling pathway in salivary gland tumors, apart from supplying information in development of potential biomarkers for these tumors.

Apoptose nas glândulas salivares humanas: avaliação de marcadores durante o processo de morfogênese da glândula / Apoptosis in human salivary glands: evaluation of markers during the gland morphogenesis

As glândulas salivares são estruturas formadas por um sistema de ductos e ácinos responsáveis por secretar saliva. Originadas pelo mecanismo de morfogênese, apresentam cinco estágios de diferenciação: pré-botão, botão inicial, pseudoglandular, canalicular e botão terminal. A compreensão da morfogênese das glândulas salivares é importante para o esclarecimento dos mecanismos de tumorigênese e os componentes das neoplasias derivadas dessas glândulas. Estudos demonstram que o processo de apoptose desempenha um papel importante na formação do lúmen durante a organogênese, sendo assim, este estudo propõe a avaliação da expressão das proteínas envolvidas no mecanismo de morte e proliferação celular durante o desenvolvimento das glândulas salivares por meio da técnica de imunoistoquímica destacando os marcadores BCL2, Survivina, Ki-67, PAR4, FAS, FASL, PHLDA1, Caspase-3 clivada, SPARC e MUC1. Adicionalmente foram avaliados alguns espécimes para as proteínas Caspase-3 total e Caspase-7. Para tanto foram selecionados 50 espécimes de glândulas salivares dissecadas de fetos humanos em diferentes estágios gestacionais, provenientes de abortos espontâneos, e coletados de diferentes locais da cavidade oral. Também foram incluídas 10 amostras de glândulas salivares adultas histologicamente normais provenientes de margens cirúrgicas para comparação com a expressão na glândula em desenvolvimento. As proteínas SPARC e Caspase-3 clivada não foram expressas no parênquima glandular. A proteína MUC1 foi positiva em padrão citoplasmático a partir da fase pseudoglandular nas regiões de abertura luminal primitiva. PHLDA1 foi observada principalmente no citoplasma e raras células com positividade nuclear em quase todas as fases do desenvolvimento, exceto no botão terminal

Salivary glands are structures formed by a system of ducts and acini responsible for secreting saliva. Salivary glands morphogenesis is divided into five differentiation stages: pre-bud, initial bud, pseudoglandular, canalicular and terminal bud. Understanding the morphogenesis of the salivary glands is important to clarify the mechanisms of tumorigenesis and the components of tumors originated in these glands. Studies show that the process of apoptosis plays an important role in the formation of the lumen during organogenesis. Therefore, in this study the expression of proteins involved in the mechanism of cell death and cellular proliferation was investigated during the development of salivary glands by immunohistochemistry using the markers BCL2, Survivin, Ki-67, PAR4, FAS, FASL, PHLDA1, cleaved Caspase-3, SPARC and MUC1. Additionally, some specimens were evaluated for total Caspase-3 and Caspase-7 proteins. For this purpose, 50 specimens of salivary glands dissected from fetuses in different gestational stages, from miscarriages, and collected from different sites of the oral cavity were selected. We also included 10 specimens of histologically normal adult salivary glands from surgical margins to compare with the expression during gland development. SPARC and cleaved Caspase-3 were not expressed in the glandular parenchyma. MUC1 protein was positive from the pseudoglandular stage in a cytoplasmic pattern in regions of early luminal opening. PHLDA1 was observed mainly in cytoplasmic pattern and rare nuclear positivity in all development phases, except in terminal bud. FAS and FASL protein were expressed, simultaneously, with membrane pattern in rare cells during glandular development. PAR4 showed positivity in all phases, except pre-acinar areas